Electrocardiography signal extraction method

Abstract

An electrocardiography signal extraction method includes receiving an electrocardiography signal, detecting a peak of a waveform of the electrocardiography signal, separating the waveform into left and right waves, normalizing the left wave and a plurality of scales of Gaussian function, comparing the normalized left wave with a left part of the normalized scales of Gaussian function, acquiring a left part error function, indicating a left minimum comparative error, selecting a left scale of Gaussian function with the left minimum comparative error, obtaining a left duration of the waveform, normalizing the right wave, comparing the normalized right wave with a right part of the normalized scales of Gaussian function, acquiring a right part error function, indicating a right minimum comparative error, selecting a right scale of Gaussian function with the right minimum comparative error, obtaining a right duration of the waveform, and obtaining an extracted wave.

What is claimed is: 
     
         1 . An electrocardiography signal extraction method for reducing the effect of the baseline drift of an electrocardiography signal retrieved by a signal retriever, the electrocardiography signal extraction method being performed on a processor of a computer system along with a predetermined database, the electrocardiography signal extraction method comprising:
 receiving the electrocardiography signal by the processor of the computer system;   detecting a peak of a waveform of the electrocardiography signal;   separating the waveform into a left wave and a right wave, wherein the left wave is the portion of the waveform to the left of the detected peak and the right wave is the portion of the waveform to the right of the detected peak;   normalizing the left wave and a plurality of scales of a Gaussian function;   comparing the normalized left wave with a left part of the normalized scales of the Gaussian function;   acquiring a left part error function according to the compared result of the normalized left wave and the left part of the normalized scales of the Gaussian function;   indicating a left minimum comparative error;   selecting a left scale of the Gaussian function with the left minimum comparative error;   obtaining a left duration of the waveform according to the selected left scale of the Gaussian function and the peak;   normalizing the right wave;   comparing the normalized right wave with a right part of the normalized scales of the Gaussian function;   acquiring a right part error function according to the compared result of the normalized right wave and the right part of the normalized scales of the Gaussian function;   indicating a right minimum comparative error;   selecting a right scale of the Gaussian function with the right minimum comparative error;   obtaining a right duration of the waveform according to the selected right scale of the Gaussian function and the peak;   obtaining an extracted wave from the detected peak, the selected left duration and the selected right duration; and   displaying the extracted wave on a display of the computer system,   wherein the Gaussian function is represented by   
       
         
           
             
               
                 
                   
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       wherein f1 is a sampling rate of the signal retriever, wherein f2 is a sampling rate of the predetermined database, wherein a ratio of v1 to f2 is 0.12-0.2. 
     
     
         2 . The electrocardiography signal extraction method for reducing the effect of the baseline drift in the electrocardiography signal as claimed in  claim 1 , further comprising de-noising the waveform before separating the waveform. 
     
     
         3 . The electrocardiography signal extraction method for reducing the effect of the baseline drift in the electrocardiography signal as claimed in  claim 1 , wherein the left wave and the right wave are normalized at the same time. 
     
     
         4 . The electrocardiography signal extraction method for reducing the effect of the baseline drift in the electrocardiography signal as claimed in  claim 1 , wherein the waveform comprises a P wave and a T wave of the electrocardiography signal. 
     
     
         5 . The electrocardiography signal extraction method for reducing the effect of the baseline drift in the electrocardiography signal as claimed in  claim 1 , wherein detecting the peak of the waveform of the electrocardiography signal comprises:
 performing a time-frequency transformation on the received electrocardiography signal;   selecting a scale for the waveform by indicating a pre-defined scale;   performing a time-frequency transformation on the selected scale to generate a transferred response; and   obtaining the peak of the waveform by detecting a maximum voltage value of the transferred response.   
     
     
         6 . The electrocardiography signal extraction method for reducing the effect of the baseline drift in the electrocardiography signal as claimed in  claim 5 , wherein obtaining the peak of the waveform by detecting the maximum voltage value of the transferred response comprises obtaining a P peak of the waveform by detecting a first maximum voltage value of the transferred response before a R peak. 
     
     
         7 . The electrocardiography signal extraction method for reducing the effect of the baseline drift in the electrocardiography signal as claimed in  claim 5 , wherein obtaining the peak of the waveform by detecting the maximum voltage value of the transferred response comprises obtaining a T peak of the waveform by detecting a first maximum voltage value of the transferred response behind a R peak. 
     
     
         8 . The electrocardiography signal extraction method for reducing the effect of the baseline drift in the electrocardiography signal as claimed in  claim 5 , wherein the time-frequency transformation comprises Continuous Wavelet Transform, Continuous Wavelet transform with Gabor mother wavelet, Gabor Wavelet Transform, Short-Time Fourier Transform or Wavelet Transform. 
     
     
         9 . The electrocardiography signal extraction method for reducing the effect of the baseline drift in the electrocardiography signal as claimed in  claim 5 , wherein obtaining the peak of the waveform comprises obtaining a R peak of the waveform by detecting a maximum voltage. 
     
     
         10 . The electrocardiography signal extraction method for reducing the effect of the baseline drift in the electrocardiography signal as claimed in  claim 9 , further comprising selecting two additional scales for the waveform by indicating two additional pre-defined scales. 
     
     
         11 . The electrocardiography signal extraction method for reducing the effect of the baseline drift in the electrocardiography signal as claimed in  claim 1 , wherein the ratio of v1 to f2 is 0.16.